1. Field
Embodiments of the present disclosure relate to an air conditioner to control a defrosting operation and a control method thereof.
2. Description of the Related Art
An air conditioner is a device that cools, heats, or purifies and discharges suctioned air using movement of heat generated during evaporation and condensation of refrigerant to condition air in an interior space.
In summer, the air conditioner performs a cooling operation to discharge heat out of a room. In winter, the air conditioner performs a heating operation of a heat pump to supply heat into the room by circulating refrigerant in reverse order of a cooling cycle.
When the air conditioner performs the heating operation, an outdoor heat exchanger of an outdoor unit absorbs heat as the result of evaporation. At this time, the surface temperature of the outdoor heat exchanger is greatly reduced with the result that condensed water is formed on the surface of the outdoor heat exchanger.
When the temperature of the outdoor heat exchanger is 0° C. or less, the condensed water does not fall down the outdoor heat exchanger but is frozen on the surface of the outdoor heat exchanger.
The condensed water frozen on the surface of the outdoor heat exchanger reduces a heat exchange area of the outdoor heat exchanger. As a result, heat exchange performance of the outdoor heat exchanger is reduced. In addition, heating efficiency of the air conditioner and reliability of a compressor are deteriorated.
For this reason, the air conditioner performs a defrosting operation, in which the refrigerant is circulated as in the cooling operation, to defrost the outdoor heat exchanger.
That is, when the cooling operation is performed during the heating operation, the refrigerant in the outdoor heat exchanger is condensed with the result that the refrigerant radiates heat, which defrosts the outdoor heat exchanger.
In the defrosting operation, however, the refrigerant flows in the same direction as in the cooling operation during the heating operation. Consequently, two-phase refrigerant, which is not overcooled, passes through an expansion valve of an indoor unit with a result that noise is generated.
In addition, the air conditioner uses change in temperature of the outdoor heat exchanger to determine entry time of the defrosting operation. When outdoor temperature is low, lowering of evaporation pressure for heat exchange between the outdoor heat exchanger and outdoor air may not be differentiated from lowering of evaporation pressure due to frost on the outdoor heat exchanger with the result that the entry time of the defrosting operation may not be accurately determined.
Consequently, the defrosting operation may be frequently performed even when the outdoor heat exchanger is unfrosted or the defrosting operation may be performed in a state in which the outdoor heat exchanger is excessively frosted. In the latter case, the outdoor heat exchanger may not be sufficiently defrosted.